0501 GMT January 20, 2018
With Japan on holiday, speculators drove the yen through 107.00 per dollar for the first time since October 2014, Reuters reported.
Often seen as a sign of broader risk aversion among investors, the move coupled with a decline on Wall Street overnight to pushed Asian and European stocks into the red.
US futures pointed to a lower open on Wall Street.
"With data continuing to show the economy is stuck in a rut and deflation returning, the last thing the BOJ need to see is a stronger yen," Rabobank analysts wrote in a note on Friday.
"For global markets there are worrying messages. Conventional monetary policy is at its limits, and, it seems, maybe so is unconventional monetary policy. If so, we are stuck in this environment. This is as good as it gets."
MSCI's broadest index of Asia-Pacific shares outside Japan lost 0.5 percent, on track for a decline of 1.7 percent for the week. That would be its biggest weekly loss in over two months.
The index of 300 leading European shares was down 1.2 percent in early trade at 1,357 points, while the German DAX , France's CAC 40 and Britain's FTSE 100 were all down around one percent too.
Surprisingly strong first quarter growth figures from Spain and France supported the euro, pushing it above $1.14. A high exchange rate hurts exporters, however, and European stocks suffered accordingly.
First quarter US and European earnings reports continued to stream in. Notable was Amazon's upbeat figures that sent the stock up almost 13 percent, easing the gloom after shed three percent when billionaire investor Carl Icahn said he no longer has a position in the tech giant.
Japan's Nikkei was closed on Friday for the Golden Week holidays which will run into next week, but closed 5.2 percent lower this week.
The yen is up more than four percent against the dollar, putting it on track for its best week since the depths of the global crisis in October 2008 and one of its best weeks since the 1990s.
It had been at 111.67 yen per dollar before Thursday's surprise decision by the BOJ not to ease policy further.
The dollar remained on the back foot following Thursday's GDP data that showed the US economy virtually ground to a halt in the first quarter, expanding at only at 0.5 percent annualized pace. That was the slowest growth in two years.
The dollar index, a measure of the greenback's value against a basket of currencies, fell 0.4 percent on Friday and was on course for its third consecutive monthly decline, something not seen for five years.
"The decline in US yields leaves the dollar vulnerable and we remain long euro/dollar, looking for the pair to reach $1.16 in the next two months," BNP Paribas currency strategists said on Friday.
Elsewhere in currency markets China's central bank fixed the yuan 0.5 percent higher on Friday, marking its biggest one-day appreciation since the landmark revaluation in July 2005.